There is 7 types of encoder:-
(1) Rotary encoder or Shaft encoder :- An Electro-
Mechanical device which converts the angular position of
shaft or axel to an analog or digital code, making it
(2) Incremental Encoder :- It is sometimes called a
(3) Absolute Position encoder :- These are used to generate
an electrical signal that indicates absolute machanical
position, or an incremental mechanical movement relative to
a refrence position.
(4) Quadrature Encoder :- the most common type of
inremental encoder uses 2 output channel (A and B) to sence
(5) Linear Encoder :- it is a sensor, transducer or
readhead paired with scale that encodes position.
(6) Open Collector Encoder :- the encoder supplied is
equipped with an npn open collector configuration which if
wired direct to counter module would require the counter
module to source current.
Will measure the position of a shaft for single rotation.
the same shaft angle will produce same reading.
# Output of encoder is gray code or binary code.
Incremental encoder: (relativ encoder)
Will give two output pulse, that can be used to measure
# logic gates and software used to determine rotation
and count pulses to determine the displacement. the
velocity can be determined time between the pulses.
We use ungrounded DC system (220V/110V) for control and
protection system in substations etc. Suppose we have long
2 core DC cables running from our DCDB in control room to
the load (length of around 2 to 3 km). Do we need to
protect these long DC cables from earth leakages or not? If
To prevent the mal operation of a differentially connected
relay while energizing a transformer, the relay restraining
coil is baised with
(a)second harmonic current
(b)fifth harmonic current
(c)third harmonic current
(d)seventh harmonic current